discover --listmodes crashes with Qt 5.9.2. Works fine with 5.9.1. ASSERT failure in QList<T>::at: "index out of range", file /usr/include/qt/QtCore/qlist.h, line 541 Thread 1 "plasma-discover" received signal SIGABRT, Aborted. 0x00007ffff35f08a0 in raise () from /usr/lib/libc.so.6 (gdb) bt #0 0x00007ffff35f08a0 in raise () from /usr/lib/libc.so.6 #1 0x00007ffff35f1f09 in abort () from /usr/lib/libc.so.6 #2 0x00007ffff3d90858 in QMessageLogger::fatal(char const*, ...) const () from /usr/lib/libQt5Core.so.5 #3 0x00007ffff3d8bc0b in qt_assert_x(char const*, char const*, char const*, int) () from /usr/lib/libQt5Core.so.5 #4 0x00005555555691b4 in QList<QObject*>::at (i=0, this=0x7fffffffe2f0) at /usr/include/qt/QtCore/qlist.h:541 #5 DiscoverMainWindow::rootObject (this=<optimized out>) at /build/discover/src/discover-5.11.0/discover/DiscoverMainWindow.cpp:404 #6 0x0000555555569ee3 in DiscoverMainWindow::modes (this=<optimized out>) at /build/discover/src/discover-5.11.0/discover/DiscoverMainWindow.cpp:130 #7 0x0000555555565b96 in main (argc=<optimized out>, argv=<optimized out>) at /build/discover/src/discover-5.11.0/discover/main.cpp:137
Possibly related: running plasma-discover (without parameters) hangs and the application never starts. Again, no issues with Qt 5.9.1 Thread 1 "plasma-discover" received signal SIGINT, Interrupt. 0x00007ffff36a7d4b in poll () from /usr/lib/libc.so.6 (gdb) bt #0 0x00007ffff36a7d4b in poll () at /usr/lib/libc.so.6 #1 0x00007fffedcf0ed3 in () at /usr/lib/libglib-2.0.so.0 #2 0x00007fffedcf0fae in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0 #3 0x00007ffff3fe4cd1 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #4 0x00007ffff3f8848b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5 #5 0x00007ffff3f914d8 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5 #6 0x0000555555565d8a in main(int, char**) (argc=<optimized out>, argv=<optimized out>) at /build/discover/src/discover-5.11.0/discover/main.cpp:151
Reverting this commit in qtdeclarative fixes both issues https://github.com/qt/qtdeclarative/commit/98358715930739ca8de172d88c5ce6941c275ff3
Backporting 36fc062a77257e5d744fe4029149fc05a71db4b2 fixes the crash, but it breaks the UI since Helpers is still used in 5.11
So you don't have the issue if you clear the cache?
Removing ~/.cache/discover doesn't make any difference
I backported the Helpers removal into 5.11. I could reproduce this issue on my system too. Thanks a lot Antonio for the bug!